Safety air nozzle

ABSTRACT

Disclosed is a safety air nozzle which can be used to inexpensively adapt a standard air blow gun to comply with the provisions of the Occupational Safety and Health Act, Section 1910.242(b). The nozzle consists of a single piece of pipe threaded on one end for attachment to a standard air blow gun and having lateral ports through the tube wall equally spaced circumferentially about the pipe. Each lateral port extends in a direction inclined outwardly toward the discharge end of the nozzle. The lateral ports allow escape of air to form an air shield which guards the air gun operator from chips blown back toward him and also to form pressure relief holes which prevent excessive pressure buildup in the event the discharge end of the nozzle become obstructed.

United States Patent 1191 Kinsley 111- 3,790,084 Feb. 5, 1974 [5 SAFETY AIR NOZZLE [75] Inventor: George R. Kinsley, Wilmington, Del.

[73] Assignee: 'Scott Paper Company, Delaware County, Pa.

221 Filed: July 14,1972 21 .Appl. 1105271921 56] References Cited UNITED STATES PATENTS 1,326,483 12 1919 Doran 239/291 2,320,964 6/1943 Yates 239/291 2,604,361 7/1952 Yates 239/291 2,783,092 2/1957 Gavin et a1. 239/291 2,917,244 12/1959 Gould 239/291 3,117,726 1/1964 Schoberg... 239/291 3,318,534 5/1967 Stoltben 239/291 3,129,892 4/1964 Tillman 239/4l7.3 3,647,142 3/1972 Drude et al 239/288.3 3,263,934 8/1966 Hope, Jr. et a1. 239/556 9/1964 France 239/291 885,892 11/197] Canada ..239/525 Primary Examiner-Lloyd L. King Attorney, Agent, or FirmR. D. Vickrey; .l. W. Kane; W. .1, Foley [57] ABSTRACT Disclosed is a safety air nozzle which can be used to inexpensively adapt a standard air blow gun to comply with the provisions of the Occupational Safety and Health Act, Section 1910.242(b). The nozzle consists of a single piece of pipe threaded on one end for attachment to a standard air blow gun and having lateral ports through the tube wall equally spaced circumferentially about the pipe. Each lateral port extends in a direction inclined outwardly toward the discharge end of the nozzle, The lateral ports allow escape of air to form an air shield which guards the air gun operator from chips blown back toward him and also to form pressure relief holes which prevent excessive pressure buildup in the event the discharge end of the nozzle become obstructed.

3 Claims, 1 Drawing Figure AIR FLOW PMENTEB FEB 51974 lllllv O E m3 SAFETY AIR NOZZLE BACKGROUND OF THE INVENTION 1. Field of the Invention I My invention relates to air blow guns of the type used for cleaning or chip removal.

2. Description of the Prior Art Air blow guns used in industrial plants and maintenance shops for cleaning or chip removal basically consist of a nozzle connected to a hose supplying air under pressure. Commercially made guns are obtainable with a number of variations. For example, they may be in the shape of a pistol for convenient holding by an operator. Also, they may include an on'off valve actuatable by a button or trigger to facilitate brief periods of use. And they may include safety devices to protect the operator. As would be expected, the more complex the cluded Section l9l0.242(b) in the Occupational Safety and Health Act to assure that such hazards are prevented. That subsection states, Compressed air shall not be used for cleaning purposes except where reduced to less than 30 psi and then only with effective chip guarding and personal protective equipment.

A number of manufacturers of air guns have included devices on their air "guns to prevent these hazards. Some include pressure regulators to maintain the air pressure below 30 psi. The pressure regulators can satisfactorily prevent overpressuring, but they are costly.

Other manufacturersinclude flow-restriction'orifices in the guns or nozzles to prevent the air pressure output from exceeding 30 psi. The orifices perform satisfactorily when the air is flowing through the nozzle in normal use, but if the discharge end of the nozzle becomes obstructed, such as can occur when the nozzle is inadvertently placed against an object, the air pressure in the nozzle will suddenly increase to full line pressure, typically 100 psi or more.

Another type of gun'co'm bines a flow-restricting orifice with a safety relief valve to prevent overpressuring in the event the discharge end of the nozzle becomes obstructed. A disadvantage'of this type of gun is that safety relief valves are either of the type which are costly or they often require repair after each discharge through them.

Yet another type of gun combines a flow-restricting orifice with a nozzle having lateral ports to provide pressure relief under static conditions. In this type of gun the ports extend through the nozzle Wall perpendicularly to the centerline of the nozzle, this disposition being chosen to minimize air leakage through the lateral ports during normal operation.

A number ofmanufacturers of air guns have also included chip guard devices. One such device consists of an annular passageway in the gun disposed coaxially to the nozzle and inclined at an acute angle to the nozzle. The annular passageway allows some of the air passing through the gun to escape and form a conical air curtain extending from the gun toward the area being cleaned by the gun. Another such device consists of a series of very small holes spaced circumferentially around the gun and disposed coaxial and parallel to the centerline of the nozzle. In these devices, the annular passageways or holes are disposed in the gun upstream of the nozzle.

In some types of air guns, these chip guard devices have been used in combination with pressure regulators, flow-restricting orifices, or relief valves. An air gun having this combination can be suitable for complying with OSHA Section l9l0.242( b), however, they are costly. In many cases, older style air guns which many industrial plants and maintenance shops have in large numbers are not readily adaptable to include this combination. In such cases, it has been necessary to discard the old air' guns and buy the newer, costly types. SUMMARY OF THE INVENTION I have discovered a very inexpensive device which can be used to adapt the older style air guns to comply with OSHA Section l9l0.242(b). My invention consists of a single pipe adaptable on one end for attachnot beexcessive, yet if the end of the nozzle is obstructed, the amount of air discharged through the lateral ports will be sufficient to prevent excessive buildup of air pressure in the nozzle. Furthermore, a sufficient amount of air will be discharged through the lateral ports during normal operations to form a conical shaped air curtain which will prevent chips from being blown back against the operator.

BRIEF DESCRIPTION OF THE DRAWING The drawing illustrates the air nozzle 1 have invented.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The illustrated nozzle consists of a cylindrical pipe 1 which has athreaded end 2. suitable for screwing into the .end of -a typical commercially available air gun which can be purchased from such suppliers as Milton Manufacturing Company, Inc. of Chicago, Ill; Branford Vibrator Company of New Britain, Conn.; Jet Engineering Company of Albuquerque, N. Mex; and others. Extending through the walls of the pipe 1 are a plurality of round lateral ports 3 equally spaced around the circumference of the pipe 1 and inclined from the centerline of the pipe outwardly toward the downstream end 4 of the pipe 1.

The size of the lateral ports 3 in my air nozzle can be varied within limits and still produce satisfactory results. To stay within the limits of my invention, each lateral port 3 should have a diameter d which is no smaller than about one-fourth and no larger than about threefourths of the inside diameter D of the pipe 1. Lateral ports 3 which have a diameter d of about one-half as large as the diameter D of the pipe 1 have been found particularly satisfactory.

The number of lateral ports 3 can be varied somewhat and still produce satisfactory results, but there should be at least three in order to produce a conical air curtain continuous about its circumference which is necessary to form an effective chip guard. In cases where the operating air pressure will be high and the lateral port size is small, a number of lateral ports greater than three may be necessary. For example, l have found that a nozzle connected to a 100 psi source of air requires the number of lateral ports which will give a combined passageway area equal to at least onehalf of the passageway area through the center of the nozzle in order to develop no more than a 30 psi static pressure in the nozzle when the discharge end is plugged. On that basis, if the size of the lateral ports diameter d are only one-fourth the size of the inside diameter D of the nozzle, then the number oflateral ports must be at least eight. Since the physical size of the lateral ports limit their maximum number in a single circumferential row, it may be necessary in some cases to have two or more circumferential rows of lateral ports. In such cases, it is preferable that there be at least one primary circumferential row which has at least three equally spaced lateral ports in it, in order to assure an effective chip guard. Where the lateral ports have a diameter d equal to about one-half of the inside diameter D of the pipe 1, it has been found that four lateral ports 3 located in a single circumferential row is a particularly satisfactory number.

The angle a at which the lateral ports are inclined from the centerline of the pipe 1 can also be varied within limits and produce satisfactory results. It is of course necessary that the angle of the air curtain be suitable to protect the operator from chips. Therefore, the angle a should be between about and about 45. An inclinationof has been found to work quite well. v

The size of the pipe 1 is dependent upon the size and type of connection to the air gun, which is typically Vs inches n.p.t. Of course, it is possible to reduce or increase the size of the discharge end 4 of the pipe 1 from the size of the air gun connection, but in keeping with the inexpensive and simple design which characterizes my invention, it is preferable to use an ordinary pipe nipple having a uniform diameter throughout. The length of the pipe 1 can be varied to any desired length longer than about Z inches. Typically, a length of about 3 inches is satisfactory. The material can be any type which is adequate to withstand the operating pressures and is easily machinable to produce the nozzle. I have found astandarcl light-weight carbon steel pipe nipple to work quite satisfactorily.

The most inexpensive and simple form of my invention is a pipe nipple with the lateral ports 3 being drilled into the walls of the nipple. However, it is to be recog nized that my invention also encompasses a nozzle which is a hollow tube having a shape other than circular and/or one having lateral ports other than circular. In such cases where the nozzle tube 1 and/or the lateral ports 3 are not circular, the formula set forth above for determining the limits for the size proportions isto be modified to reflect proportions of passageway areas. For example, the satisfactory diameter d for circular lateral ports 3 has been set forth as between about onefourth and about three-fourths ofthe inside diameter D of the nozzle tube 1. This proportion represents a passageway area proportion of from about one-sixteenth to about nine-sixteenths.

Even where the nozzle tube 1 is not circular, the spacing of lateral ports 3 should be based upon a circular line which is coaxial with the centerline of the tube 1. In such a case, the term circumferentially" as used in this specification and claims refers to that circular line.

It is also to be recognized that the lateral ports 3 which are located in the primary circumferential row do not necessarily have to be located exactly on a common circumferential line, but the circumferential spacing between the ports 3 should be generally equal around the tube 1. However, it is preferable that the lateral ports 3 of the primary circumferential row be located close enough to a common circumferential line to form a generally conical air curtain.

What is claimed is:

1. A safety air gun nozzle comprising:

a hollow tube for conveying the air; and

a plurality of lateral ports extending through the tube wall in spaced locations about the perimeter of the tube for allowing escape of air in the event of flow obstruction of the discharge end of the tube and for forming an air curtain to shield the air gun operator from chips and debris which might otherwise be blown back against him;

the passageway area of each lateral port being between about one-sixteenth and about ninesixteenths of the passageway area of the tube in order to prevent excessive static pressure buildup in the event of flow obstruction of the discharge end of the tube without excessive diversion of air from the tube during normal operation, but with sufficient diversion of air through the lateral ports during normal operation to form an effective air curtain; 4

the circumferential spacing of the lateral ports being generally equal about the tube and the number of lateral ports being at least three in order to form a continuous air curtain about the nozzle; and

each lateral port extending through the tube wall in a direction inclined outwardly toward the discharge end of the nozzle at an angle from the centerline of the tube of between about 15 to about 45 in order to form an effective generally conical air curtain.

2. The safety air gun nozzle according to claim 1 wherein the hollow tube and the lateral ports are circular.

3. The safety air gun nozzle according to claim 2 wherein: I

the diameter of each lateral port is about one-half of the diameter of the inside of the tube;

the number of lateral ports is four; and

each lateral port extends through the tube wall in a direction inclined outwardly toward the discharge end of the nozzle at an angle from the centerline of the tube of about 30. 

1. A safety air gun nozzle comprising: a hollow tube for conveying the air; and a plurality of lateral ports extending through the tube wall in spaced locations about the perimeter of the tube for allowing escape of air in the event of flow obstruction of the discharge end of the tube and for forming an air curtain to shield the air gun operator from chips and debris which might otherwise be blown back against him; the passageway area of each lateral port being between about one-sixteenth and about nine-sixteenths of the passageway area of the tube in order to prevent excessive static pressure buildup in the event of flow obstruction of the discharge end of the tube without excessive diversion of air from the tube during normal operation, but with sufficient diversion of air through the lateral ports during normal operation to form an effective air curtain; the circumferential spacing of the lateral ports being generally equal about the tube and the number of lateral ports being at least three in order to form a continuous air curtain about the nozzle; and each lateral port extending through the tube wall in a direction inclined outwardly toward the discharge end of the nozzle at an angle from the centerline of the tube of between about 15* to about 45* in order to form an effective generally conical air curtain.
 2. The safety air gun nozzle according to claim 1 wherein the hollow tube and the lateral ports are circular.
 3. The safety air gun nozzle according to claim 2 wherein: the diameter of each lateral port is about one-half of the diameter of the inside of the tube; the number of lateral ports is four; and each lateral port extends through the tube wall in a direction inclined outwardly toward the discharge end of the nozzle at an angle from the centerline of the tube of about 30*. 